In the first session, after an accurate evaluation of spaces and residual dental tissues and the acceptance of this type of treatment by the patient, pillar teeth were prepared using diamond bur on high speed handpiece with mesio-occlusal, disto-occlusal, MOD, onlay or overlay preparations according to each clinical situation. Cavity preparation is required not only to remove all carious tissue, but to create a minimal space necessary to the glass fibers to support occlusal loads. According to "Munack" a cavity with 2x2mm occlusal surface and 2mm depth is able to support a 600N masticatory stress before breaking, and by increasing depth to 4mm we can reach 700N.